Emergency workers continued to search for bodies and plane fragments that could serve as evidence, but bad weather slowed their efforts. A helicopter scheduled to fly low over the crash site so experts could inspect it could not make the trip because of heavy, low cloud cover.

The Tupolev 154, en route from Tel Aviv, Israel, to Novosibirsk, Russia, exploded Thursday and crashed into the sea 114 miles off the Russian coastal city of Adler, near Sochi. Most of the 66 passengers were recent Russian immigrants to Israel, and many were heading back to their homeland to visit relatives over the Jewish Sukkot holiday.

U.S. intelligence officials have said the plane was hit by a Ukrainian missile during exercises. After initially dismissing the U.S. allegations, Russian officials appeared to be considering the possibility Saturday.

Russian Defense Minister Sergei Ivanov said President Vladimir Putin had been dissatisfied with the information that Ukraine had sent to Moscow on its military exercises, saying it had been inadequate. Ivanov said he asked for more, including technical details on the missile launches.

"All versions must be considered, including the interconnection with the Ukrainian air defense exercises," Ivanov said in comments broadcast on Russian television.

Like Ukrainian officials, Ivanov had previously denied even the possibility that a Ukrainian missile could have brought the plane down. On Friday, he said dismissively that the "so-called version" of events had been "launched by the media" and asked the Pentagon to send proof of its assertion.

In a telephone conversation Saturday night, Putin and Ukrainian President Leonid Kuchma agreed that no theory should be ruled out, the Interfax news agency reported. Earlier in the day, Kuchma had reiterated Ukraine's stance that a missile strike was impossible.

"The missiles' route was completely different from that of the airplane," Kuchma said during a visit to Poland.

Vladimir Rushailo, the head of Putin's security council, told reporters in Sochi on Saturday that investigators confirmed the plane was "hit by an explosion." He said a large number of similar punctures were found on fragments from the body of the plane and its interior.

He said that "objects" that were not part of the plane had also been found and said they were being examined for identification. He refused to comment on what those objects might be.

However, two officials involved with the salvage effort described a cylindrical object that they could not immediately identify.

U.S. intelligence officials believe the plane was hit by a Ukrainian S-200, or SA-5, missile a large surface-to-air missile built to shoot down heavy bombers flying at high altitudes.